1. Field of the Invention
The present invention relates to a circuit breaker device that breaks an electric circuit in a short time.
2. Description of the Related Art
In an electric equipment system provided on a vehicle, a large current fuse that has been disposed between the battery and the wire harness is cut off by fusion when some abnormality or other has occurred, for example, in a load, such as a power window, or in a wire harness constructed of a plurality of electric wires connecting a battery and each load, etc. By doing so, a break is made between the battery and the wire harness to thereby prevent the respective loads or wire harness from being damaged by burning.
However, in such an electric equipment system using a large current fuse, even when some abnormality or other has occurred in a load, such as a power window, or in a wire harness constructed of a plurality of electric wires connecting a battery and each load, etc., the large current fuse is not cut off by fusion unless an electric current of a magnitude greater than a permissible value that is preset in the large current fuse occurs. In this view, there have been developed protection apparatuses of bi-metal type and fusible conductor type that sense this flowage and makes a break between the battery and the wire harness when a large current of a magnitude near the permissible value is continuously flowing therethrough.
However, in the protection apparatus of bi-metal type, using a bi-metal, wherein two kinds of metal whose coefficients of thermal expansion differ from each other, it is detected whether a large current is flowing through a fusible member. Therefore, when the magnitude of the current flowing through the fusible member is changed, the bi-metal is deformed with the result that the length of time that is needed until the breakage of the circuit changes.
For this reason, when a trouble has occurred, such as that wherein a large magnitude of current intermittently flows, it happens that the temperature of the fusible member ceases to rise beyond a certain value of temperature. As a result, there was the possibility that the wire harness or the load excessively generated heat before the protection apparatus broke the circuit.
On the other hand, in the protection apparatus of fusible conductor type, using a coil made of a shape memory alloy, it is detected whether a large magnitude of current is flowing through the fusible conductor line. Therefore, when the magnitude of the current flowing through the fusible conductor line is changed, the coil is deformed, with the result that the length of time that is needed until the breakage of the circuit changes.
For this reason, when a large magnitude of current intermittently flows, it happens that the temperature of the fusible conductor line ceases to rise beyond a certain value of temperature. As a result, there was the possibility that the wire harness or the load excessively generated heat before the protection apparatus broke the circuit. Also, in a case where using bi-metal or shape memory alloy, the temperature at which the deformation starts is ordinarily as low as approximately 100xc2x0 C. Therefore, bi-metal or shape memory alloy was difficult to use at a temperatures of 120xc2x0 C. to 125xc2x0 C., which is the environmental-of-use conditions of a vehicle.
Also, in both protection apparatuses, the response-to-heat length of time of the bi-metal or coil, which is a heat-deformable electricity conductor member, was influenced by the passage of current through it. Furthermore, there were cases where at the time of an abnormality (the passage of current in excess) the response to heat of the heat-deformable electricity conductor member did not occur timely.
An object of the present invention is to provide a circuit breaker device that when an abnormality signal on the vehicle can break the circuit shortly and reliably, and protect a relevant electric circuit.
To achieve the above object, the present invention provides a circuit breaker device. The device has a first connection terminal; a heating portion which is filled with a heating agent and has a conductivity; and a first contact member for conductively joining the heating portion to the first connection terminal. The first contact member has contact portions and opening portions.
Preferably, each of the opening portions is a slit portion which consists of a slender groove.
Preferably, each of the contact portions and the slit portions are alternately formed.
Preferably, the first contact member is mounted to the first connection terminal, and the contact portions are brought in contact with the heating portion.
Preferably, the-first contact member is mounted to the eating portion, and the contact portions are brought in contact with the first connection terminal.
Preferably, the device further has a second connection terminal; and a second contact member for conductively joining the heating portion to the second connection terminal. The second contact member has contact portions and opening portions.
Preferably, the device further has a claw portion which is lockingly engaged with the heating portion.
Preferably, the claw portion is made of resin.
Preferably, the device further has an outer vessel which is fixed with the claw portion. The outer vessel accommodates the heating portion.
Preferably, the device further has an elastic member which is arranged to contact with the heating portion. The elastic member is for biasing the heating portion to the claw portion.
Preferably, the device further has an ignition portion for igniting the heating agent by an abnormal signal from outside at abnormality of a vehicle.
Preferably, the outer vessel has an upper casing and a lower casing. The upper casing is formed with a first threaded portion. The lower portion is formed with a second threaded portion which is screwed to the first threaded portion.
Preferably, the device further has an outer vessel which accommodates the heating portion. The first connection terminal is integrally formed to the outer vessel.
Preferably, the device further has an out vessel which accommodates the heating portion. The second connection terminal is integrally formed to the outer vessel.
Preferably, the heating agent is a thermit agent which has a metal oxide powder and an aluminum powder mixed with the metal oxide powder.
According to the present invention, for example, a first connection terminal or a second connection terminal is connected to a heating portion via a first or second contact member, whereby a power is supplied from a battery to a load. Also, when an ignition portion gets ignited due to an abnormality signal from outside, a heating agent filled in the heating portion generates heat, whereby due to this heat, claw portions, each formed on an outer vessel and made of resin material, are melted. For this reason, an elastic member is expanded with the result that the heating portion is pushed upward while sliding on the first or second contact member. Therefore, the electric connection between the heating portion and one of the first and the second connection terminals is cut off. Therefore, it is possible to cut off the circuit shortly and reliably and to thereby protect relevant electric parts.
Also, since the first or second contact member is a multi-contact spring, and wherein slit portions consisting of a slender groove and contact portions electrically contacted with the heating portion are formed alternately two or more in number, the resistance to sliding is small. Therefore, it is possible to easily cut off the circuit and, in addition, since the resistance to contact is small, it is possible to lessen the generation of heat when a large current passes through.
Also, when an upper casing is fitted onto a lower casing, a first threaded portion formed on the upper casing is screwed onto a second threaded portion formed on the lower casing. As a result, when breakage of the circuit is done, the heating portion ceases to pop out, nor is there a fear that a relevant person will be scorched due to the heat.
Also, since the first or the second connection terminal is formed integrally with the outer vessel, only a small number of parts items to be assembled are needed, with the result that the number of operation steps can be reduced.
Also, the heating agent can generate a heat of thermit reaction due to the thermit reaction.